A patient who is prone to irregular heart rhythms may have a miniature heart device, such as defibrillator and cardioverter, implanted in his or her body. Devices such as these detect the onset of an abnormal heart rhythm and apply a corrective electrical therapy to the heart.
A defibrillator or cardioverter generally includes one or more leads, a battery for supplying power, circuitry for detecting an abnormal heart rhythm, and a capacitor for delivering a burst of electric current through one or more leads to the heart. The battery, circuitry and capacitor are typically contained in a housing. The one or more leads typically have a proximal end coupled to the housing and a distal end secured in or around the heart.
The basic components that make up a battery are an anode, a cathode, and a separator between the anode and the cathode. A battery typically also includes an electrolyte and packaging hardware, which may include a medical device housing.